The stipules are arranged in two ranks, inserted on the stem at right angles to the tendrils. They increase in size as the plant gains in vigour, and become obliquely triangular-hastate, but continue flat in bud and afterwards. The venation consists of numerous parallel nerves, radiating from the point of insertion on the stem, the midrib being slightly the strongest (fig. 304). FIG. 305.-LATHY- Succeeding pairs of stipules overlap and protect all the younger members of the terminal and axillary leaf- and flower-buds and tendrils. All lateral buds come in the axils of the tendrils. The stipules, therefore, perform the double function of leaves and the work of protection. A very interesting contrast is afforded by another species of Lathyrus (L. Nissolia), where the leaves are reduced (fig. 307) to a long, linear, grass-like, flattened leaf-stalk, ending in a fine point, and without leaflets. In the mature plant the stipules are almost obsolete, but in the seedling first and second leaves are subulate, acute, and scale-like, with small tooth-like or inconspicuous stipules. The third and all succeeding leaves are simple, entire, linear, slightly decurrent (fig. 306) the upon the stem, and have a strong midrib, with more slender parallel lateral nerves. They are alternate and S FIG. 306.-SEEDLING OF LATHYRUS NISSOLIA. Nat. size. S, seed. distichous-that is, on the plan of arrangementacuminate, and slightly narrowed to the base. The third and all succeeding pairs of stipules are subulate acute, slender, gradually becoming-shorter FIG. 307.-LATHYRUS NISSOLIA. towards the apex of the stem, and inserted on the edge of the decurrent leaf, where it is narrowed, and below the articulation with the stem. They appear to be functionless owing to their minute size. The terminal bud is enclosed in successive convolute leaves, which appear to be winged petioles without leaflets or tendril. They vary from three inches to six in length, and attain a considerable size before they unroll, after which they continue to be more or less concave, becoming slightly twisted. The axillary buds are sheltered in their axils. The terminal bud is amply protected by them. The plant forms a spreading tuft like a species of grass with coarse leaves. The same causes which have led to the length and narrowness of the leaves of grass have probably influenced Lathyrus Nissolia, as well as other species which grow under similar circumstances. The resemblance is perhaps, also an advantage in preventing its being picked out and eaten by browsing quadrupeds. CHAPTER VII ON THE SUBSIDIARY USES OF STIPULES THE general use of stipules is, as we have seen, to cover and protect the bud. This is, however, by no means the only function they perform. Though very 1" -st FIG. 308.-SHOOT OF HOLLY, showing successive leaves (', ', ') and stipules (st, st). often leafy, they are generally too small to be of much use as organs of assimilation. There are, however, various gradations. Some, indeed, are quite minute, as in the Holly (fig. 308) and Hymenanthera (fig. 29, p. 24). In other cases, though smaller than the leaf-blades, the stipules assist in performing similar functions. In some the assimilation must be trifling, as in the stipulate species of Helianthemum, in Ribes, and many others; in others it is substantial, though less than in the leaf-blades, as in the Roses; in others equal to that of the leaf-blades, as in the Pansy (fig. 309), where the stipules are large, oblong, and pinnatifid, with three to six linear lobes on the external side; or Galium |